The Culture Secretary agreed a charity wager with TV presenter Piers Morgan when challenged about the impact losing the referendum would have on Mr Cameron's political future.

Piers Morgan had a bet live on air with John Whittingdale that David Cameron will fall if we vote to leave the European Union (Ken McKay/ITV/REX/Shuttersto​ck)

Mr Cameron has said he will not seek a third term as prime minister and he is expected to come under intense pressure to quit if he suffers the humiliation of ending up on the losing side after the June 23 referendum.

Mr Whittingdale, one of five full Cabinet members who have expressed their support for a vote to break from Brussels, in opposition to the Prime Minister, said Mr Cameron had already achieved a better deal for the UK if it voted to stay and he would lead negotiations if the country decided to leave.

He told ITV's Good Morning Britain: "Even if we vote to stay in, we will be in a better place than we were before under the old terms.

"If the British people decide that it is not enough and that we should leave, then he will respect that decision and he will be the first to go and negotiate a new deal so that we do get the best possible outcome."

He added: "If we win the campaign, then I am confident the Prime Minister will continue in office."

Piers Morgan had a bet live on air with John Whittingdale that David Cameron will fall if we vote to leave the European Union (Ken McKay/ITV/REX/Shuttersto​ck)

Morgan challenged the minister: "I will bet you £1,000 to charity that if you guys win - and you may well - David Cameron has two hopes of remaining Prime Minister: No hope and Bob Hope."

The Cabinet minister shook hands on the wager and Morgan tweeted:

Just bet @JWhittingdale £1000 on air that Cameron won't be PM if he loses EU referendum. He accepted... eventually.